Since the invention of the integrated circuit (IC), the semiconductor industry has experienced rapid growth due to continuous improvements in the integration density of a variety of electronic components. For the most part, this improvement in integration density has come from repeated reductions in minimum feature size, which allows more components to be integrated into a given area. As the demand for even smaller electronic devices has grown, there has grown a need for smaller and more creative packaging technologies of semiconductor dies.
Conventional packaging technologies divide a wafer into separate dies and package each individual die, following a sequence of placing a single die on the package substrate, forming first-level interconnects generally via wire bond or flip chip, encapsulation, test, inspection, and second level interconnect to the circuit board in final assembly. These technologies and processes are time consuming.
Wafer level package (WLP) technology is the technology of packaging dies at wafer level. WLP technology can produce dies with small dimensions and good electrical properties, and is currently widely used for its low cost and relatively simple processes. WLP technology basically extends the wafer fab processes to include device interconnection and device protection processes. In WLP technology, back end of line (BEOL) processes involve a few mask layers beginning with a polymer dielectric layer, a redistribution layer, an under bump metallization, and wafer bumping all prior to dicing. Sometimes encapsulation is also performed at wafer level before the entire wafer is singulated in the dicing process.
Dicing is the process by which dies are separated from a wafer. The dicing process can be accomplished by scribing and breaking, by mechanical sawing (normally with a machine called a dicing saw) or by laser cutting. In WLP technology, the encapsulation material such as a molding compound may cover scribe lines of the wafers and reduce the die sawing accuracy. Methods and apparatus are needed to increase the die sawing accuracy for WLP packages in the dicing process.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the various embodiments and are not necessarily drawn to scale.